Adjustable impedance welding transformer



April 29, 1958 R. F. BRENNEN ET AL 2,832,939

ADJUSTABLE} IMPEDANCE WELDING TRANSFORMER Filed Feb. 16,- 1956 INVENTORS RONALD F. BHENNEN JAMES A. BUCCI Z ATTORNEY United States. Patent O ADJUSTABLE IMPEDANCE WELDING TRANSFORMER Ronald F. Brennen and James A. Bucci, Brooklyn, N. Y.,

assignors to Welding Industry Research & Patent Corporation, New York, N. Y., a corporation of New York Application August 16, 1956, Serial No. 604,551

6 Claims. (Cl. 336-45) This invention relates to electrical transformers and more particularly to adjustable impedance step down transformers for electric welding though it is noted that in some of the claims the invention is not limited to step down or welding transformers.

Objects of the invention are to provide an improved transformer of this kind having no inside connections or contacts and having a minimum of moving parts.

Other objects of the invention are to provide an im- 1 proved transformer of small weight giving a large current,

and having an adjustable impedance giving a wide range of current with fine adjustments clearly indicated.

Additional objects of the invention are to effect simplicity and efliciency in such apparatus and to provide an extremely simple compact transformer of this kind which is easy and accurate in adjustment, economical, durable, and reliable in operation, and economical to manufacture and transport.

Still other objects of the invention will appear as the description proceeds; and while herein details of the invention are described in the specification and some of the claims, the invention as described in the broaderclaims is not limited to these, and many and various changes maybe made without departing from the scope of the invention as claimed in the broader claims.

The inventive features for the accomplishment of these and other objects are shown in connection with an adjustable impedance transformer, which briefly stated comprises a toroidal core having a primary winding therearound, and completely annular channel races disposed adjacent to the inner curved face of the wound core. A secondary winding is wound around about 180 degrees of the toroidal core and said races. An arcuate choke core about 180 long and disposed for travel in said races and into and out of the secondary winding carries an indicating finger which travels adjacent to a scale plate when the choke core moves, the scale plate being marked in amperes.

When the choke core is moved further into the secondary coil the impedance is increased and the amperage is decreased and the scale is calibrated to indicate the amperage at each position of the choke core.

In the accompanying drawing showing, by way of example, one of many possible embodiments of the invention,

Fig. 1 is a front elevation of the transformer, parts being broken away and in section; and

Figs. 2 and 3 are sectional views taken on the lines 2--2 and 3-3 respectively.

The adjustable impedance transformer comprises a laminated toroidal magnetic core 10 of substantially rectangular cross section; which may be wrapped with tape not shown, around which is a primary winding 12 of insulated wire extending substantially 360 around the core and having terminal ends 14 for connection with a suitable source of alternating current. Inner and outer curved strips 16, 18 of Bakelite or other suitable insulating material are disposed around the inner and 2,832,939 Patented Apr. 29, 1958 outer curved sides of the wound core in contact with the primary windings. Front and rear flat rings 20, 22 of Bakelite or other insulating material disposed on the front and rear faces of the wound core from edge to edge thereof against the primary windings, each having at its upper half a wide overhanging part 24, about the width of the core, extended from the wound core towards the central axis of the core.

Front and rear completely annular channel races 26, 28, of aluminum or other non-magnetic material, opening toward each other have their connecting walls 30, 32 disposed respectively against said overhanging parts 24, one side wall 34 of each race being secured by friction and/or pins 36 against the inner curved strip 16.

A stiff annular connecting plate 38 of Bakelite or the like is secured by pins 40 to the other wall 42 of each race. A secondary winding 44 of insulated wires around about of the upper half of the toroidal core is wound around said fiat rings 20, 22 said wide parts 24, the outer curved strip 18 and said annular connecting plate 38 and has end leads 46 for connection with welding electrodes.

A laminated arcuate magnetic choke core 48 about 180 long disposed for travel in said races 26, 28 slightly spaced from the walls thereof is provided near its ends and midpart with transverse bearing bores 50 respectively near and parallel to said connecting walls. Shallow recesses 52 are provided in the choke core around the ends of said bores and extending through the front and rear flat faces of the choke core; and shafts 54 of fiber or other insulating materials in said bores have their ends projecting into the recesses and carrying rollers 56 in the recesses engaging said connecting walls 32 and holding the choke core spaced from the connecting walls, whereby the choke core may be moved to substantially fill the space surrounded, as shown in Fig. 1, by the secondary windings, or may be partially withdrawn or substantially fully withdrawn from said space.

The exposed part of the front connecting wall 30 not covered by said wide part 24 of the front flat ring 20 is provided midway between its edges with an arcuate slot 60 (Figs. 1 and 3) extending substantially from end-toend of said exposed part; and a flat block 62 in and projecting from said slot secured fast on an end of the choke core has mounted thereon a flat detent spring 64 extending frontwardly a distance from the block and having a narrow indicating portion 66 provided with a manipulating end ball 68. An arcuate scale plate 70 mounted on posts 72 mounted on the front connecting wall 39, along and substantially from end-to-end of the slot is provided in its edge with a plurality of spaced notches 74 in any one of which said narrow indicating portion 66 may engage to hold the choke core in adjusted position. Progressively increasing numerms 76, on the scale plate adjacent to the respective notches, indicate amperes, the smallest number being disposed adjacent to the notch in which the indicating portion engages when the choke core is furthest in the space surrounded by the secondary winding.

When the choke core 48 is moved further into the secondary winding 44 the impedance is increased thus decreasing the amperage and vice versa. The scale plate 70 is calibrated in amperes by numerals 76 to indicate the amperage at each position of the indicating portion 66.

The transformer may be mounted in any suitable frame or housing exposing the scale. I

The leads 46 are connected to welding electrodes or to any instrument for which the transformer may be in-' The invention claimed is:

1. A transformer comprising a toroidal core; a primary winding around the core; completely annular channel races disposed adjacent to the inner curved face of the wound core; a secondary winding wound around about half of the toroidal core and said races; an arcuate choke core about 180 long disposed for travel in said races; an indicating finger mounted on an end of the choke core; and a scale plate mounted adjacent to which said finger moves when the choke core moves.

2. A transformer comprising a toroidal core; a primary winding around the core; completely annular channel races disposed adjacent to the inner curved face of the wound core; a secondary winding wound around about half of the toroidal core and said races; and an arcuate choke core about 180 long disposed for travel in said races.

3. An adjustable impedance transformer comprising a toroidal magnetic core of substantially rectangular cross section; a primary winding extending substantially 360 around the core; front and rear flat insulating rings on the front and rear faces of the wound core each having at one half a Wide part extended toward the core axis; front and rear completely annular channel races opening toward each other and disposed adjacent to the inner curved side of the wound core; a secondary winding wound around about half of the toroidal core on said wide parts; an arcuate choke core about 180 long disposed for travel in said recess; a projecting finger mounted on the choke core; an arcuate scale adjacent to one of the races, adjacent to which said finger may move; and numerals indicating amperes disposed along the scale.

4. An adjustable impedance transformer comprising a magnetic toroidal core of substantially rectangular cross section; a primary winding of insulated Wire extending substantially 369 around the core; inner and outer curved strips of insulating material around the inner and outer curved sides of the Wound core; front and rear flat insulating rings on the front and rear faces of the wound core each having at its upper half a wide part extended toward the core axis; front and rear completely annular channel races opening toward each other and disposed against said wide overhanging parts, one side wall of each race being secured to the inner curved strip; an annular stiff connecting insulating plate secured to the other wall of each race; a secondary winding wound around the upper half of the toroidal core on said wide parts; an arcuate choke core about 180 long disposed for travel in said races; whereby the choke core may be moved to substantially fill all or any part or none of the space surrounded by the secondary windings.

5. A transformer comprising a toroidal core; a primary winding around the core; completely annular channel races opening toward each other disposed adjacent to the inner curved face of the wound core; a secondary winding wound around about half of the toroidal core and said races; an arcuate choke core about long disposed for travel in said races slightly spaced from the walls thereof provided near its end and mid-part with transverse bearing bores respectively near and parallel to the connecting walls, and shallow recesses in the choke core around the ends of the bores and extending through the front and rear fiat faces of the choke; shafts of fiber or other insulating materials in said bores and having their ends projecting into the recesses; rollers in the recesses on the projecting ends of the shafts engaging said projecting walls and holding the choke core spaced from the connecting walls; whereby the choke core may be moved to substantially fill the space surrounded gy the secondary windings or may be substantially withdrawn from said space; an indicating finger mounted on an end of the choke core; and a scale plate mounted adjacent to which said finger moves when the choke core moves.

6. A transformer comprising a toroidal core; a primary winding around the core; completely annular channel races opening toward each other each having inner, outer and connecting walls, one wall being disposed adjacent to the inner curved face of the wound core; a secondary Winding wound around about 180 degrees of the toroidal core and said races leaving an exposed part of each connecting wall; an arcuate choke core about 180 long disposed for travel in said races; the exposed part of one connecting wall being provided with an arcuate slot extending substantially from end-to-end of the exposed part; a block fast on an end of the choke core projecting from said slot; a yieldable finger mounted on said block; an arcuate scale plate mounted along the slot substantially from end to end thereof and provided with edge notches in which said finger may engage; and numerals indicating amperes adjacent to the respective notches.

References Cited in the file of this patent UNITED STATES PATENTS 

